fsa.py

"""
Convert sequitur model to FSA.
"""

__author__    = 'Maximilian Bisani'
__version__   = '$Revision: 1667 $'
__date__      = '$Date: 2007-06-02 16:32:35 +0200 (Sat, 02 Jun 2007) $'
__copyright__ = 'Copyright (c) 2004-2005  RWTH Aachen University'
__license__   = """
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License Version 2 (June
1991) as published by the Free Software Foundation.
 
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, you will find it at
http://www.gnu.org/licenses/gpl.html, or write to the Free Software
Foundation, Inc., 51 Franlin Street, Fifth Floor, Boston, MA 02110,
USA.
 
Should a provision of no. 9 and 10 of the GNU General Public License
be invalid or become invalid, a valid provision is deemed to have been
agreed upon which comes closest to what the parties intended
commercially. In any case guarantee/warranty shall be limited to gross
negligent actions or intended actions or fraudulent concealment.
"""

import pickle, sys
from xmlwriter import XmlWriter


def writeAsFsa(model, xml, shouldMakeClosure = True):
    sq = model.sequitur
    sm = model.sequenceModel

    xml.open('fsa',
	     initial  = 0,
	     type     = 'transducer',
	     semiring = 'tropical')

    def makeAlphabet(inv):
	for index, symbol in enumerate(inv.list):
	    xml.element('symbol', symbol, index=index)

    xml.open('input-alphabet')
    makeAlphabet(sq.leftInventory)
    xml.close('input-alphabet')

    xml.open('output-alphabet')
    for disambi in range(sq.inventory.size()):
	sq.rightInventory.index('__%d__' % (disambi+1))
    makeAlphabet(sq.rightInventory)
    xml.close('output-alphabet')

    initial = (None, None, sm.initial())
    idMap = { initial: 0 }
    open = [initial]

    def makeArc(left, right, target, weight=None):
	inp = out = None
	if left:
	    inp = left[0]
	    left = left[1:]
	if not left: left = None

	if right:
	    out = right[0]
	    right = right[1:]
	if not right: right = None

	target = (left, right, target)
	try:
	    targetId = idMap[target]
	except KeyError:
	    targetId = idMap[target] = len(idMap)
	    open.append(target)

	xml.open('arc', target=targetId)
	if inp or out:
	    xml.comment((inp or "") + ':' + (out or ''))
	if inp:
	    xml.element('in', sq.leftInventory.index(inp))
	if out:
	    xml.element('out', sq.rightInventory.index(out))
	if weight:
	    xml.element('weight', weight)
	xml.close('arc')

    while open:
	current = open.pop()
	currentId = idMap[current]
	left, right, current = current

	currentDesc = map(sq.symbol, sm.historyAsTuple(current))
	currentDesc = [''.join(ll) + ':' + '_'.join(rr)
		       for ll, rr in currentDesc ]
	if left or right:
	    currentDesc += ['/', ''.join(left or ()) + ':' + '_'.join(right or ()) ]
	currentDesc = ' '.join(currentDesc)

	xml.open('state', id=currentId)
	xml.comment(currentDesc)
	if left or right:
	    makeArc(left, right, current)
	else:
	    for predicted, score in sm.getNode(current):
		if predicted == sq.term:
		    xml.element('final')
		    xml.element('weight', score)
		if predicted is None:
		    target = sm.shortened(current)
		    if target:
			makeArc(None, None, target, score)
		elif predicted != sq.term or shouldMakeClosure:
		    target = sm.advanced(current, predicted)
		    left, right = sq.symbol(predicted)
		    right = right + ('__%d__' % predicted,)
		    makeArc(left, right, target, score)
	xml.close('state')
    xml.close('fsa')


def main(options, args):
    model = pickle.load(open(options.modelFile))
    out = sys.stdout
    writeAsFsa(model, XmlWriter(out, 'UTF-8'))

# ===========================================================================
if __name__ == '__main__':
    import optparse, tool
    optparser = optparse.OptionParser(
	usage   = '%prog [OPTION]... FILE...\n' + __doc__,
	version = '%prog ' + __version__)
    tool.addOptions(optparser)
    optparser.add_option(
	'-m', '--model', dest='modelFile',
	help='read model from FILE', metavar='FILE')
    options, args = optparser.parse_args()
    tool.run(main, options, args)